ge.rkt

#lang racket/base

(require racket/generic)

(define-generics print
  (gen-print print))

(define (print-point p)
  (format "x is ~a" (point-x p)))

(struct
  point (x)
  #:methods gen:print
  [(define gen-print print-point)])


(struct
  point2d point (y)
  #:methods gen:print
  [(define (gen-print me)
     (format "~a && y is ~a " (print-point me) (point2d-y me)))])